LaGuardia Airport closed access to Terminals C and D for hours Thursday morning due to police activity, as a suspicious package forced the evacuation of Terminal D.
The Transportation Security Administration said a passenger's checked bag set off an alarm during screening. Explosives specialists examined the bag and recommended calling in the NYPD's bomb squad, TSA said.
The owner of the bag flew to Detroit as scheduled and was being questioned there, TSA added. Airport sources tell News 4 the bag's owner claimed white powder found inside was a chemical for film development, but authorities are still testing it.
Just after 9 a.m., the airport tweeted that passengers could return to Terminal C via a walkway, and just before 9:30 a.m. the Port Authority said all the roadways had reopened. TSA also confirmed that the bag had been cleared.
NYC Emergency Management warned to "expect traffic delays, cancellations and a heavy presence of emergency personnel" on the Grand Central Parkway approaching the airport.
With limited communication, travelers took to Twitter to ask the airport what they should be doing.
Others lamented being stuck in traffic for an hour or more due to the clogged - and now closed - roadways.
This is a developing story.